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Dentistry: Guide to New Dental Amalgam Rule


For questions or more information, please email DentalAmalgam@

Send compliance forms by email to DentalAmalgam@

or by mail to:

Bureau of Environmental Services
Water Pollution Control Lab
Attn: Dental Amalgam
6543 N. Burlington Avenue
Portland, OR 97203-5452

The Environmental Protection Agency recently published chapter 40 of the Code of Federal Regulations, part 441 (40 CFR 441), the Dental Office Point Source Category. This new regulation establishes national standards for dental offices that place or replace dental amalgam and discharge to sanitary sewer systems. This new rule requires local public agencies to regulate facilities that use dental amalgam in their practice, and limit mercury discharge to publicly owned treatment works.


Dental amalgam — typically referred to as a “silver filling" — is made of two nearly equal parts; liquid mercury, and a powder containing a mixture of silver, tin, copper, zinc, and other metals. The pollutant of concern in this alloy is the heavy metal mercury, which can have a bioaccumulative toxic effect that persists when introduced into the environment, especially in aquatic ecosystems. Amalgam discharged to City of Portland wastewater treatment facilities has the potential to enter local waterways through discharge to the Willamette and Columbia Rivers. Controlling amalgam discharges benefits the health of our local ecosystems.

Who is Affected by this Rule?

This rule applies to offices, including large dental institutions and clinics, where dentistry is practiced who discharge to City wastewater treatment facilities. Facilities who are affected by this rule will be required to submit compliance certifications annually by July 15th.


New facilities that begin discharging to a publicly owned treatment plant on or after the effective date of July 15, 2017 are expected to comply immediately. Within 30 days of opening, these businesses must submit a signed Initial Compliance Certification and include proof of installation of an amalgam separator that removes 95% of solids in accordance with ISO 11143 at the new facility to: If emailing a signed scanned document, keep the original onsite. Keep any maintenance logs, and records of amalgam waste disposal from a period of up to three years. The City of Portland may conduct a site inspections to verify compliance with the rule. New sources will then be required to submit Annual Compliance Certification and accompanying documentation each following year. Change in ownership at a facility is considered a new source and the new owner must submit the Initial Compliance Certification within 30 days. 


Facilities in business before the effective date of July 15, 2017, are expected to be in compliance under the 2007 State of Oregon Senate Bill 704-B. Existing facilities will have three years from the effective date to retrofit their offices with the required equipment. Existing facilities will be required to submit Annual Compliance Certifications and supporting documentation. Supporting documentation refers to the Best Management Practices (BMPs) listed on the Annual Compliance Certification (i.e. proof of maintenance and/or off-site disposal).

Who is Exempt from this Rule?

This rule does not apply to mobile units or offices where the practice of dentistry consists only of the following dental specialties: oral pathology, oral and maxillofacial radiology, oral and maxillofacial surgery, orthodontics, periodontics, or prosthodontics. Also excluded are dental offices that do not place or remove amalgam except in limited, emergency or unplanned, unanticipated circumstances. However, these types of facilities will need to submit a one-time Initial Compliance Certification and complete the waiver request section on the form.

Rule Requirements


FORM: Initial Compliance Certification

FORM: Annual Compliance Certification

Oregon requires dental offices to meet most of the requirements of this new rule under State of Oregon Senate Bill 704-B. BMPs to be followed by all facilities affected by the rule include:

  • Treat all amalgam wastewater through properly-sized amalgam separator(s), certified to remove at least 95% of total amalgam solids, in accordance with ISO 11143.
  • Inspect the amalgam separator(s), at a minimum, once per month to ensure proper operation and confirm that there is no bypass of the treatment system.
  • Repair or replace defective amalgam removal equipment/components in accordance to the manufacturer’s instructions.
  • Regularly maintain the amalgam separator(s) by replacing retaining cartridges, separator canisters, filters, and/or other treatment units annually, or whenever the unit reaches the manufacturer’s design capacity, whichever comes first.
  • The use of oxidizing or acidic cleaners to flush dental unit water lines is prohibited.
  • Collect scrap amalgam from chair-side traps, screens, vacuum pump filters, dental tools, and/or other collection devices for off-site disposal. Scrap amalgam must not be flushed down the drain.

In addition to the Initial Compliance Certification, the City of Portland will be requiring offices to submit  Annual Compliance Certification acknowledging BMPs have been followed, and requirements have been met. Supporting documentation of installation of an amalgam separator will also be required to accompany all Initial Compliance Certifications. Documentation of proper waste disposal in accordance with local, state, and federal waste disposal regulations will be required for all Annual Compliance Certifications.

Program Fees

There is no program fee associated with the Initial Compliance Certification. However, facilities affected by this rule who are required to submit Annual Compliance Certification will be subject to an annual fee of $100 to be billed separately.